My code fragment is below: "*nl_sk = netlink_kernel_create(16, 0, nl_data_ready, THIS_MODULE);"* It can be "make" and "insmod" correctly. But error mesage is printed into log. It indicates the netlink_kernel_create() returns NULL. Once I change the firt parameter to another(<32 && >16), system crash when I execute insmod. Is the protocol ID occupied? Why can't use another and how to define a new ID? I have tried to update net_link.h but fail also. -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.centos.org/pipermail/centos-devel/attachments/20110222/4fbb922b/attachment-0006.html>